The Chilean hit a 14-minute treble as Arsenal leapfrogged Manchester City and Liverpool into second place in the Premier League table.

The 5-1 win extends Arsenal's unbeaten top flight run since the start of the season to 13 matches (nine wins and four draws), and Wenger was delighted in particular with his star striker's display at the London Stadium.

Arsenal's manager said: "We had a convincing performance and strong result. We created many chances and you could see West Ham are not a confident team at home. On top of that we had a strong performance.

Sanchez was, quite simply, unstoppable (Image: 2016 Getty Images)

"Alexis Sanchez - it took him a while mentally to get into the game, but he can always give you something special.

"He’s a fighter and a classy player. You don’t find many players like him. He can always surprise you. He also has great technique as well.

"I believe we are on a strong run and it’s down to us to be mentally ready to maintain that run."